The present invention relates to novel compounds and a composition and method for inhibiting retroviral proteases and in particular for inhibiting human immunodeficiency virus (HIV) protease, a composition and method for treating a retroviral infection and in particular an HIV infection, processes for making such compounds and synthetic intermediates employed in these processes.
Retroviruses are those viruses which utilize a ribonucleic acid (RNA) intermediate and a RNA-dependent deoxyribonucleic acid (DNA) polymerase, reverse transcriptase, during their life cycle. Retroviruses include, but are not limited to, the RNA viruses of the Retroviridae family, and also the DNA viruses of the Hepadnavirus and Caulimovirus families. Retroviruses cause a variety of disease states in man, animals and plants. Some of the more important retroviruses from a pathological standpoint include human immunodeficiency viruses (HIV-1 and HIV-2), which cause acquired immune deficiency syndrome (AIDS) in man, hepatitis B virus, which causes hepatitis and hepatic carcinomas in man, human T-cell lymphotrophic viruses I, II, IV and V, which cause human acute cell leukemia, and bovine and feline leukemia viruses which cause leukemia in domestic animals.
Proteases are enzymes which cleave proteins at specific peptide bonds. Many biological functions are controlled or mediated by proteases and their complementary protease inhibitors. For example, the protease renin cleaves the peptide angiotensinogen to produce the peptide angiotensin I. Angiotensin I is further cleaved by the protease angiotensin converting enzyme (ACE) to form the hypotensive peptide angiotensin II. Inhibitors of renin and ACE are known to reduce high blood pressure in vivo. An inhibitor of a retroviral protease will provide a therapeutic agent for diseases caused by the retrovirus.
The genomes of retroviruses encode a protease that is responsible for the proteolytic processing of one or more polyprotein precursors such as the pol and gag gene products. See Wellink, Arch. Virol. 98 1 (1988). Retroviral proteases most commonly process the gag precursor into core proteins, and also process the pol precursor into reverse transciptase and retroviral protease. In addition, retroviral proteases are sequence specific. See Pearl, Nature 328 482 (1987).
The correct processing of the precursor polyproteins by the retroviral protease is necessary for the assembly of infectious virions. It has been shown that in vitro mutagenesis that produces protease-defective virus leads to the production of immature core forms which lack infectivity. See Crawford, J. Virol. 53 899 (1985); Katoh, et al., Virology 145 280 (1985). Therefore, retroviral protease inhibition provides an attractive target for antiviral therapy. See Mitsuya, Nature 325 775 (1987).
Current treatments for viral diseases usually involve administration of compounds that inhibit viral DNA synthesis. Current treatments for AIDS involve administration of compounds such as 3xe2x80x2-azido-3xe2x80x2-deoxythymidine (AZT), 2xe2x80x2,3xe2x80x2-dideoxycytidine (DDC) and 2xe2x80x2,3xe2x80x2-dideoxyinosine (DDI) and compounds which treat the opportunistic infections caused by the immunosuppression resulting from HIV infection. None of the current AIDS treatments have proven to be totally effective in treating and/or reversing the disease. In addition, many of the compounds currently used to treat AIDS cause adverse side effects including low platelet count, renal toxicity and bone marrow cytopenia.
In accordance with the present invention, there are retroviral protease inhibiting compounds of the formula A: 
wherein R1 is monosubstituted thiazolyl, monosubstituted oxazolyl, monosubstituted isoxazolyl or monosubstituted isothiazolyl wherein the substituent is selected from (i) loweralkyl, (ii) loweralkenyl, (iii) cycloalkyl, (iv) cycloalkylalkyl, (v) cycloalkenyl, (vi) cycloalkenylalkyl, (vii) heterocyclic wherein the heterocyclic is selected from aziridinyl, azetidinyl, pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, thiomorpholinyl, thiazolyl, oxazolyl, isoxazolyl, isothiazolyl, pyridinyl, pyrimidinyl, pyridazinyl and pyrazinyl and wherein the heterocyclic is unsubstituted or substituted with a substituent selected from halo, loweralkyl, hydroxy, alkoxy and thioalkoxy, (viii) (heterocyclic)alkyl wherein heterocyclic is defined as above, (ix) alkoxyalkyl, (x) thioalkoxyalkyl, (xi) alkylamino, (xii) dialkylamino, (xiii) phenyl wherein the phenyl ring is unsubstituted or substituted with a substituent selected from halo, loweralkyl, hydroxy, alkoxy and thioalkoxy, (xiv) phenylalkyl wherein the phenyl ring is unsubstituted or substituted as defined above, (xv) dialkylaminoalkyl, (xvi) alkoxy and (xvii) thioalkoxy;
n is 1, 2 or 3;
R2 is hydrogen or loweralkyl;
R3 is loweralkyl;
R4 and R4a are independently selected from phenyl, thiazolyl and oxazolyl wherein the phenyl, thiazolyl or oxazolyl ring is unsubstituted or substituted with a substituent selected from (i) halo, (ii) loweralkyl, (iii) hydroxy, (iv) alkoxy and (v) thioalkoxy;
R6 is hydrogen or loweralkyl;
R7 is thiazolyl, oxazolyl, isoxazolyl or isothiazolyl wherein the thiazolyl, oxazolyl, isoxazolyl or isothiazolyl ring is unsubstituted or substituted with loweralkyl;
X is hydrogen and Y is xe2x80x94OH or X is xe2x80x94OH and Y is hydrogen, with the proviso that X is hydrogen and Y is xe2x80x94OH when Z is xe2x80x94N(R8)xe2x80x94 and R7 is unsubstituted and with the proviso that X is hydrogen and Y is xe2x80x94OH when R3 is methyl and R7 is unsubstituted; and
Z is absent, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94CH2xe2x80x94 or xe2x80x94N(R8)xe2x80x94 wherein R8 is loweralkyl, cycloalkyl, xe2x80x94OH or xe2x80x94NHR8a wherein R8a is hydrogen, loweralkyl or an N-protecting group; or a pharmaceutically acceptable salt, ester or prodrug thereof.
Preferred compounds of the formula A are those wherein R1 is monosubstituted thiazolyl or monosubstituted oxazolyl; n is 1; R2 is hydrogen; R4 is phenyl or thiazolyl; R4a is phenyl; R6 is hydrogen and R7 is thiazolyl, oxazolyl, isothiazolyl or isoxazolyl.
More preferred compounds of the formula A are those wherein R1 is 2-monosubstituted-4-thiazolyl or 2-monosubstituted-4-oxazolyl; n is 1; R2 is hydrogen; R4 is phenyl; R4a is phenyl; R6 is hydrogen and R7 is 5-thiazolyl, 5-oxazolyl, 5-isothiazolyl or 5-isoxazolyl.
Even more preferred compounds of the formula A are those wherein R1 is 2-monosubstituted-4-thiazolyl or 2-monosubstituted-4-oxazolyl wherein the substituent is loweralkyl; n is 1; R2 is hydrogen; R4 is phenyl; R4a is phenyl; R6 is hydrogen; R7 is 5-thiazolyl, 5-oxazolyl, 5-isothiazolyl or 5-isoxazolyl; and Z is xe2x80x94Oxe2x80x94 or xe2x80x94N(R8)xe2x80x94 wherein R8 is loweralkyl.
Most preferred compounds of the formula A are those wherein R1 is 2-monosubstituted-4-thiazolyl or 2-monosubstituted-4-oxazolyl wherein the substituent is ethyl or isopropyl; n is 1; R2 is hydrogen; R3 is methyl or isopropyl; R4 is phenyl; R4a is phenyl; R6 is hydrogen; R7 is 5-thiazolyl, 5-oxazolyl, 5-isothiazolyl or 5-isoxazolyl; and Z is xe2x80x94Oxe2x80x94.
Most preferred compounds of the formula A are also those wherein R1 is 2-monosubstituted-4-thiazolyl or 2-monosubstituted-4-oxazolyl wherein the substituent is ethyl or isopropyl; n is 1; R2 is hydrogen; R4 is isopropyl; R4 is phenyl; R4a is phenyl; R6 is hydrogen; R7 is 5-thiazolyl, 5-oxazolyl, 5-isothiazolyl or 5-isoxazolyl; and Z is xe2x80x94N(R8)xe2x80x94 wherein R8 is methyl.
Most preferred compounds of the formula A are also those wherein the configuration of the carbon atom bearing xe2x80x94CH2R4 is xe2x80x9cSxe2x80x9d and the configuration of the carbon bearing X is xe2x80x9cSxe2x80x9d when X is xe2x80x94OH and the configuration of the carbon atom bearing Y is xe2x80x9cSxe2x80x9d when Y is xe2x80x94OH and the configuration of the carbon atom bearing xe2x80x94CH2(R5-substituted phenyl) is xe2x80x9cSxe2x80x9d.
Preferred compounds of the invention are compounds of the formula A1: 
wherein R1 is monosubstituted thiazolyl, monosubstituted oxazolyl, monosubstituted isoxazolyl or monosubstituted isothiazolyl wherein the substituent is selected from (i) loweralkyl, (ii) loweralkenyl, (iii) cycloalkyl, (iv) cycloalkylalkyl, (v) cycloalkenyl, (vi) cycloalkenylalkyl, (vii) heterocyclic wherein the heterocyclic is selected from aziridinyl, azetidinyl, pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, thiomorpholinyl, thiazolyl, oxazolyl, isoxazolyl, isothiazolyl, pyridinyl, pyrimidinyl, pyridazinyl and pyrazinyl and wherein the heterocyclic is unsubstituted or substituted with a substituent selected from halo, loweralkyl, hydroxy, alkoxy and thioalkoxy, (viii) (heterocyclic)alkyl wherein heterocyclic is defined as above, (ix) alkoxyalkyl, (x) thioalkoxyalkyl, (xi) alkylamino, (xii) dialkylamino, (xiii) phenyl wherein the phenyl ring is unsubstituted or substituted with a substituent selected from halo, loweralkyl, hydroxy, alkoxy and thioalkoxy, (xiv) phenylalkyl wherein the phenyl ring is unsubstituted or substituted as defined above, (xv) dialkylaminoalkyl, (xvi) alkoxy and (xvii) thioalkoxy;
n is 1, 2 or 3;
R2 is hydrogen or loweralkyl;
R3 is loweralkyl;
R4 is phenyl, thiazolyl or oxazolyl wherein the phenyl, thiazolyl or oxazolyl ring is unsubstituted or substituted with a substituent selected from (i) halo, (ii) loweralkyl, (iii) hydroxy, (iv) alkoxy and (v) thioalkoxy;
R5 is hydrogen, halo, loweralkyl, hydroxy, alkoxy or thioalkoxy;
R6 is hydrogen or loweralkyl;
R7 is thiazolyl, oxazolyl, isoxazolyl or isothiazolyl wherein the thiazolyl, oxazolyl, isoxazolyl or isothiazolyl ring is unsubstituted or substituted with loweralkyl;
X is hydrogen and Y is xe2x80x94OH or X is xe2x80x94OH and Y is hydrogen, with the proviso that X is hydrogen and Y is xe2x80x94OH when Z is xe2x80x94N(R8)xe2x80x94 and R7 is unsubstituted and with the proviso that X is hydrogen and Y is xe2x80x94OH when R3 is methyl and R7 is unsubstituted;
Z is absent, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94CH2xe2x80x94 or xe2x80x94N(R8)xe2x80x94 wherein R8 is loweralkyl, cycloalkyl, xe2x80x94OH or xe2x80x94NHR8a wherein R8a is hydrogen, loweralkyl or an N-protecting group; or a pharmaceutically acceptable salt, ester or prodrug thereof.
Preferred compounds of the formula A1 are those wherein R1 is monosubstituted thiazolyl or monosubstituted oxazolyl; n is 1; R2 is hydrogen; R4 is phenyl or thiazolyl; R5 is hydrogen; R6 is hydrogen and R7 is thiazolyl, oxazolyl, isothiazolyl or isoxazolyl.
More preferred compounds of the formula A1 are those wherein R1 is 2-monosubstituted-4-thiazolyl or 2-monosubstituted-4-oxazolyl; n is 1; R2 is hydrogen; R4 is phenyl; R5 is hydrogen; R6 is hydrogen and R7 is 5-thiazolyl, 5-oxazolyl, 5-isothiazolyl or 5-isoxazolyl.
Even more preferred compounds of the formula A1 are those wherein R1 is 2-monosubstituted-4-thiazolyl or 2-monosubstituted-4-oxazolyl wherein the substituent is loweralkyl; n is 1; R2 is hydrogen; R4 is phenyl; R5 is hydrogen; R6 is hydrogen; R7 is 5-thiazolyl, 5-oxazolyl, 5-isothiazolyl or 5-isoxazolyl; and Z is xe2x80x94Oxe2x80x94 or xe2x80x94N(R8)xe2x80x94 wherein R8 is loweralkyl.
Most preferred compounds of the formula A1 are those wherein R1 is 2-monosubstituted-4-thiazolyl or 2-monosubstituted-4-oxazolyl wherein the substituent is ethyl or isopropyl; n is 1; R2 is hydrogen; R3 is methyl or isopropyl; R4 is phenyl; R5 is hydrogen; R6 is hydrogen; R7 is 5-thiazolyl, 5-oxazolyl, 5-isothiazolyl or 5-isoxazolyl; and Z is xe2x80x94Oxe2x80x94.
Most preferred compounds of the formula A1 are also those wherein R1 is 2-monosubstituted-4-thiazolyl or 2-monosubstituted-4-oxazolyl wherein the substituent is ethyl or isopropyl; n is 1; R2 is hydrogen; R3 is isopropyl; R4 is phenyl; R5 is hydrogen; R6 is hydrogen; R7 is 5-thiazolyl, 5-oxazolyl, 5-isothiazolyl or 5-isoxazolyl; and Z is xe2x80x94N(R8)xe2x80x94 wherein R8 is methyl.
Most preferred compounds of the formula A1 are also those wherein X is hydrogen and Y is xe2x80x94OH.
Most preferred compounds of the formula A1 are also those wherein the configuration of the carbon atom bearing xe2x80x94CH2R4 is xe2x80x9cSxe2x80x9d and the configuration of the carbon bearing X is xe2x80x9cSxe2x80x9d when X is xe2x80x94OH and the configuration of the carbon atom bearing Y is xe2x80x9cSxe2x80x9d when Y is xe2x80x94OH and the configuration of the carbon atom bearing xe2x80x94CH2(R5-substituted phenyl) is xe2x80x9cSxe2x80x9d.
In accordance with the present invention, there are also retroviral protease inhibiting compounds of the formula A2: 
wherein R1 is monosubstituted thiazolyl, monosubstituted oxazolyl, monosubstituted isoxazolyl or monosubstituted isothiazolyl wherein the substituent is selected from (i) loweralkyl, (ii) loweralkenyl, (iii) cycloalkyl, (iv) cycloalkylalkyl, (v) cycloalkenyl, (vi) cycloalkenylalkyl, (vii) heterocyclic wherein the heterocyclic is selected from aziridinyl, azetidinyl, pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, thiomorpholinyl, thiazolyl, oxazolyl, isoxazolyl, isothiazolyl, pyridinyl, pyrimidinyl, pyridazinyl and pyrazinyl and wherein the heterocyclic is unsubstituted or substituted with a substituent selected from halo, loweralkyl, hydroxy, alkoxy and thioalkoxy, (viii) (heterocyclic)alkyl wherein heterocyclic is defined as above, (ix) alkoxyalkyl, (x) thioalkoxyalkyl, (xi) alkylamino, (xii) dialkylamino, (xiii) phenyl wherein the phenyl ring is unsubstituted or substituted with a substituent selected from halo, loweralkyl, hydroxy, alkoxy and thioalkoxy, (xiv) phenylalkyl wherein the phenyl ring is unsubstituted or substituted as defined above, (xv) dialkylaminoalkyl, (xvi) alkoxy and (xvii) thioalkoxy;
n is 1, 2 or 3;
R2 is hydrogen or loweralkyl;
R3 is loweralkyl;
R4 and R4a are independently selected from phenyl, thiazolyl and oxazolyl wherein the phenyl, thiazolyl or oxazolyl ring is unsubstituted or substituted with a substituent selected from (i) halo, (ii) loweralkyl, (iii) hydroxy, (iv) alkoxy and (v) thioalkoxy;
R6 is hydrogen or loweralkyl;
R7 is thiazolyl, oxazolyl, isoxazolyl or isothiazolyl wherein the thiazolyl, oxazolyl, isoxazolyl or isothiazolyl ring is unsubstituted or substituted with loweralkyl;
X is xe2x80x94OH and Y is xe2x80x94OH; and
Z is absent, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94CH2xe2x80x94 or xe2x80x94N(R8)xe2x80x94 wherein R8 is loweralkyl, cycloalkyl, xe2x80x94OH or xe2x80x94NHR8a wherein R8a is hydrogen, loweralkyl or an N-protecting group; or a pharmaceutically acceptable salt, ester or prodrug thereof.
Preferred compounds of the formula A2 are those wherein R1 is monosubstituted thiazolyl or monosubstituted oxazolyl; n is 1; R2 is hydrogen; R4 is phenyl or thiazolyl; R4a is phenyl; R6 is hydrogen and R7 is thiazolyl, oxazolyl, isothiazolyl or isoxazolyl.
More preferred compounds of the formula A2 are those wherein R1 is 2-monosubstituted-4-thiazolyl or 2-monosubstituted-4-oxazolyl; n is 1; R2 is hydrogen; R4 is phenyl; R4a is phenyl; R6 is hydrogen and R7 is 5-thiazolyl, 5-oxazolyl, 5-isothiazolyl or 5-isoxazolyl.
Even more preferred compounds of the formula A2 are those wherein R1 is 2-monosubstituted-4-thiazolyl or 2-monosubstituted-4-oxazolyl wherein the substituent is loweralkyl; n is 1; R2 is hydrogen; R4 is phenyl; R4a is phenyl; R6 is hydrogen; R7 is 5-thiazolyl, 5-oxazolyl, 5-isothiazolyl or 5-isoxazolyl; and Z is xe2x80x94Oxe2x80x94 or xe2x80x94N(R8)xe2x80x94 wherein R8 is loweralkyl.
Preferred compounds of the formula A2 are also those wherein the configuration of the carbon atom bearing xe2x80x94CH2R4 is xe2x80x9cSxe2x80x9d and the configuration of the carbon atom bearing xe2x80x94CH2(R5-substituted phenyl) is xe2x80x9cSxe2x80x9d.
The compounds of the invention comprise asymmetrically substituted centers (i.e., asymmetrically substituted carbon atoms). The present invention is intended to include all stereoiosomeric forms of the compounds, including racemic mixtures, mixtures of diastereomers, as well as single diastereomers of the compounds of the invention. The terms xe2x80x9cSxe2x80x9d and xe2x80x9cRxe2x80x9d configuration are as defined by the IUPAC 1974 Recommendations for Section E, Fundamental Stereochemistry, Pure Appl. Chem. (1976) 45, 13-30.
The terms xe2x80x9cValxe2x80x9d and xe2x80x9cAlaxe2x80x9d as used herein refer to valine and alanine, respectively. Unless otherwise noted, when xe2x80x9cValxe2x80x9d and xe2x80x9cAlaxe2x80x9d are used herein they refer to the L-isomer. In general, the amino acid abbreviations used herein follow the IUPAC-IUB Joint Commission on Biochemical Nomenclature for amino acids and peptides (Eur. J. Biochem. 1984, 158, 9-31).
The term xe2x80x9cN-protecting groupxe2x80x9d or xe2x80x9cN-protectedxe2x80x9d as used herein refers to those groups intended to protect the N-terminus of an amino acid or peptide or to protect an amino group against undersirable reactions during synthetic procedures. Commonly used N-protecting groups are disclosed in Greene, xe2x80x9cProtective Groups In Organic Synthesis,xe2x80x9d (John Wiley and Sons, New York (1981)), which is hereby incorporated by reference. N-protecting groups comprise acyl groups such as formyl, acetyl, propionyl, pivaloyl, t-butylacetyl, 2-chloroacetyl, 2-bromoacetyl, trifluoroacetyl, trichloroacetyl, phthalyl, o-nitrophenoxyacetyl, xcex1-chlorobutyryl, benzoyl, 4-chlorobenzoyl, 4-bromobenzoyl, 4-nitrobenzoyl, and the like; sulfonyl groups such as benzenesulfonyl, p-toluenesulfonyl and the like; carbamate forming groups such as benzyloxycarbonyl, p-chlorobenzyloxycarbonyl, p-methoxybenzyloxycarbonyl, p-nitrobenzyloxycarbonyl, 2-nitrobenzyloxycarbonyl, p-bromobenzyloxycarbonyl, 3,4-dimethoxybenzyloxycarbonyl, 3,5-dimethoxybenzyloxycarbonyl, 2,4-dimethoxybenzyloxycarbonyl, 4-methoxybenzyloxycarbonyl, 2-nitro-4,5-dimethoxybenzyloxycarbonyl, 3,4,5-trimethoxybenzyloxycarbonyl, 1-(p-biphenylyl)-1-methylethoxycarbonyl, xcex1,xcex1-dimethyl-3,5-dimethoxybenzyloxycarbonyl, benzhydryloxycarbonyl, t-butyloxycarbonyl, diisopropylmethoxycarbonyl, isopropyloxycarbonyl, ethoxycarbonyl, methoxycarbonyl, allyloxycarbonyl, 2,2,2,-trichloroethoxycarbonyl, phenoxycarbonyl, 4-nitrophenoxycarbonyl, fluorenyl-9-methoxycarbonyl, cyclopentyloxycarbonyl, adamantyloxycarbonyl, cyclohexyloxycarbonyl, phenylthiocarbonyl and the like; alkyl groups such as benzyl, triphenylmethyl, benzyloxymethyl and the like; and silyl groups such as trimethylsilyl and the like. Preferred N-protecting groups are formyl, acetyl, benzoyl, pivaloyl, t-butylacetyl, phenylsulfonyl, benzyl, t-butyloxycarbonyl (Boc) and benzyloxycarbonyl (Cbz).
The term xe2x80x9cO-protecting groupxe2x80x9d as used herein refers to a substituent which protects hydroxyl groups against undesirable reactions during synthetic procedures such as those O-protecting groups disclosed in Greene, xe2x80x9cProtective Groups In Organic Synthesis,xe2x80x9d (John Wiley and Sons, New York (1981)). O-protecting groups comprise substituted methyl ethers, for example, methoxymethyl, benzyloxymethyl, 2-methoxyethoxymethyl, 2-(trimethylsilyl)ethoxymethyl, t-butyl, benzyl and triphenylmethyl; tetrahydropyranyl ethers; substituted ethyl ethers, for example, 2,2,2-trichloroethyl; silyl ethers, for example, trimethylsilyl, t-butyldimethylsilyl and t-butyldiphenylsilyl; and esters prepared by reacting the hydroxyl group with a carboxylic acid, for example, acetate, propionate, benzoate and the like.
The term xe2x80x9cloweralkylxe2x80x9d as used herein refers to straight or branched chain alkyl radicals containing from 1 to 6 carbon atoms including, but not limited to, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, n-pentyl, 1-methylbutyl, 2,2-dimethylbutyl, 2-methylpentyl, 2,2-dimethylpropyl, n-hexyl and the like.
The term xe2x80x9cloweralkenylxe2x80x9d as used herein refers to a straight or branched chain alkyl radical containing from 2 to 6 carbon atoms and also having one carbon-carbon double bond including, but not limited to, vinyl, 2-propenyl, 2-methyl-2-propenyl, 3-butenyl, 4-pentenyl, 5-hexenyl and the like.
The term xe2x80x9cphenylxe2x80x9d as used herein refers to a phenyl group which is unsubstituted or substituted with a substituent selected from loweralkyl, alkoxy, thioalkoxy, hydroxy and halo.
The term xe2x80x9cphenylalkylxe2x80x9d as used herein refers to an phenyl group appended to a loweralkyl radical including, but not limited to, benzyl, 4-hydroxybenzyl, 4-chlorobenzyl, 1-naphthylmethyl and the like.
The term xe2x80x9calkylaminoxe2x80x9d as used herein refers to a loweralkyl radical appended to an xe2x80x94NH radical.
The term xe2x80x9ccycloalkylxe2x80x9d as used herein refers to an aliphatic ring having 3 to 7 carbon atoms including, but not limited to, cyclopropyl, cyclopentyl, cyclohexyl and the like. A preferred cycloalkyl group is cyclopropyl
The term xe2x80x9ccycloalkylalkylxe2x80x9d as used herein refers to a cycloalkyl group appended to a loweralkyl radical, including but not limited to cyclohexylmethyl.
The term xe2x80x9ccycloalkenylxe2x80x9d as used herein refers to to an aliphatic ring having 5 to 7 carbon atoms and also having one carbon-carbon double bond including, but not limited to, cyclopentenyl, cyclohexenyl and the like.
The term xe2x80x9ccycloalkenyalkylxe2x80x9d as used herein refers to a cycloalkenyl group appended to a loweralkyl radical including, but not limited to, cyclopentenylmethyl, cyclohexenylmethyl and the like.
The terms xe2x80x9calkoxyxe2x80x9d and xe2x80x9cthioalkoxyxe2x80x9d as used herein refer to R15Oxe2x80x94 and R15Sxe2x80x94, respectively, wherein R15 is a loweralkyl group or benzyl.
The term xe2x80x9calkoxyalkylxe2x80x9d as used herein refers to an alkoxy group appended to a loweralkyl radical.
The term xe2x80x9cthioalkoxyalkylxe2x80x9d as used herein refers to a thioalkoxy group appended to a loweralkyl radical.
The term xe2x80x9cdialkylaminoxe2x80x9d as used herein refers to xe2x80x94NR16R17 wherein R16 and R17 are independently selected from loweralkyl groups.
The term xe2x80x9cdialkylaminoalkylxe2x80x9d as used herein refers to xe2x80x94NR18R19 which is appended to a loweralkyl radical wherein R18 and R19 are independently selected from loweralkyl.
The term xe2x80x9chaloxe2x80x9d or xe2x80x9chalogenxe2x80x9d as used herein refers to xe2x80x94Cl, xe2x80x94Br, xe2x80x94I or xe2x80x94F.
The term xe2x80x9cheterocyclicxe2x80x9d as used herein refers to a heterocyclic group selected from aziridinyl, azetidinyl, pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, thiomorpholinyl, thiazolyl, oxazolyl, isoxazolyl, isothiazolyl, pyridinyl, pyrimidinyl, pyridazinyl and pyrazinyl and wherein the heterocyclic is unsubstituted or substituted with a substituent selected from halo, loweralkyl, hydroxy, alkoxy and thioalkoxy.
The term xe2x80x9c(heterocyclic)alkylxe2x80x9d as used herein refers to a heterocyclic group appended to a loweralkyl radical including, but not limited to, pyrrolidinylmethyl and morpholinylmethyl.
The term xe2x80x9cactivated ester derivativexe2x80x9d as used herein refer to acid halides such as acid chlorides, and activated esters including, but not limited to, formic and acetic acid derived anhydrides, anhydrides derived from alkoxycarbonyl halides such as isobutyloxycarbonylchloride and the like, N-hydroxysuccinimide derived esters, N-hydroxyphthalimide derived esters, N-hydroxybenzotriazole derived esters, N-hydroxy-5-norbornene-2,3-dicarboxamide derived esters, 2,4,5-trichlorophenol derived esters and the like.
In the compounds of the invention, combinations of substituents and/or variables are permissible only if such combinations result in stable compounds. As used herein, the term xe2x80x9cstable compoundxe2x80x9d refers to a compound that is sufficiently stable to survive isolation to a useful degree of purity from a reaction mixture and formulation into a therapeutic dosage form suitable for administration.
Preferred compounds of the invention are selected from the group consisting of:
(2S,3S,5S)-5-(N-(N-((N-Methyl-N-((2-isopropyl-4-thiazolyl)methyl)amino)carbonyl)valinyl)amino)-2-(N-((5-thiazolyl)methoxycarbonyl)amino)-1,6-diphenyl-3-hydroxyhexane;
(2S,3S,5S)-5-(N-(N-((N-Methyl-N-((2-isopropyl-4-thiazolyl)methyl)amino)carbonyl)alaninyl)amino)-2-(N-((5-thiazolyl)methoxycarbonyl)amino)-1,6-diphenyl-3-hydroxyhexane;
(2S,3S,5S)-5-(N-(N-((2-Isopropyl-4-thiazolyl)methoxycarbonyl)valinyl)amino)-2-(N-((5-thiazolyl)methoxycarbonyl)amino)-1,6-diphenyl-3-hydroxyhexane;
(2S,3S,5S)-2-(N-(N-((2-Isopropyl-4-thiazolyl)methoxycarbonyl)valinyl)amino)-5-(N-((5-thiazolyl)methoxycarbonyl)amino)-1,6-diphenyl-3-hydroxyhexane;
(2S,3S,5S)-5-(N-(N-((2-Isopropyl-4-thiazolyl)methoxycarbonyl)alaninyl)amino)-2-(N-((5-thiazolyl)methoxycarbonyl)amino)-1,6-diphenyl-3-hydroxyhexane;
(2S,3S,5S)-5-(N-(N-((2-(N,N-Dimethylamino)-4-thiazolyl)methoxycarbonyl)valinyl)amino)-2-(N-((5-thiazolyl)methoxycarbonyl)amino)-1,6-diphenyl-3-hydroxyhexane;
(2S,3S,5S)-2-(N-(N-((2-(N,N-Dimethylamino)-4-thiazolyl)methoxycarbonyl)valinyl)amino)-5-(N-((5-thiazolyl)methoxycarbonyl)amino)-1,6-diphenyl-3-hydroxyhexane;
(2S,3S,5S)-5-(N-(N-((2-(4-Morpholinyl)-4-thiazolyl)methoxycarbonyl)valinyl)amino)-2-(N-((5-thiazolyl)methoxycarbonyl)amino-1,6-diphenyl-3-hydroxyhexane;
(2S,3S,5S)-2-(N-(N-((2-(4-morpholinyl)-4-thiazolyl)methoxycarbonyl)valinyl)amino)-5-(N-((5-thiazolyl)methoxycarbonyl)amino)-1,6-diphenyl-3-hydroxyhexane;
(2S,3S,5S)-5-(N-(N-((2-(1-Pyrrolidinyl)-4-thiazolyl)methoxycarbonyl)valinyl)amino)-2-(N-((5-thiazolyl)methoxycarbonyl)amino)-1,6-diphenyl-3-hydroxyhexane;
(2S,3S,5S)-5-(N-(N-((N-Methyl-N-((2-isopropyl-4-oxazolyl)methyl)amino)carbonyl)valinyl)amino)-2-(N-((5-thiazolyl)methoxycarbonyl)amino)-1,6-diphenyl-3-hydroxyhexane;
(2S,3S,5S)-5-(N-(N-((N-Methyl-N-((2-isopropyl-4-oxazolyl)methyl)amino)carbonyl)valinyl)amino)-2-(N-((5-oxazolyl)methoxycarbonyl)amino)-1,6-diphenyl-3-hydroxyhexane;
(2S,3S,5S)-5-(N-(N-((N-Methyl-N-((2-isopropyl-4-thiazolyl)methyl)amino)carbonyl)valinyl)amino)-2-(N-((5-oxazolyl)methoxycarbonyl)amino)-1,6-diphenyl-3-hydroxyhexane;
(2S,3S,5S)-5-(N-(N-((N-Methyl-N-((2-isopropyl-4-thiazolyl)methyl)amino)-1,6-carbonyl)valinyl)amino)-2-(N-((5-isoxazolyl)methoxycarbonyl)amino)-1,6-diphenyl-3-hydroxyhexane; and
(2S,3S,5S)-5-(N-(N-((N-Methyl-N-((2-isopropyl-4-oxazolyl)methyl)amino)carbonyl)valinyl)amino)-2-(N-((5-isoxazolyl)methoxycarbonyl)amino)-1,6-diphenyl-3-hydroxyhexane; or a pharmaceutically acceptable salt, ester or prodrug thereof.
Compounds useful as intermediates for the preparation of the compound of formula A and A1 include the compound of the formula A3: 
wherein R4 and R4a are independently selected from phenyl, thiazolyl and oxazolyl wherein the phenyl, thiazolyl or oxazolyl ring is unsubstituted or substituted with a substituent selected from (i) halo, (ii) loweralkyl, (iii) hydroxy, (iv) alkoxy and (v) thioalkoxy; and R* is phenyl, halo-substituted phenyl, dihalo-substituted phenyl, alkoxy-substituted phenyl, loweralkyl-substituted phenyl, bis-trifluromethyl-substituted phenyl or naphthyl or loweralkyl; or an acid addition salt thereof.
Preferred intermediates are compounds of the formula A4: 
wherein R4 and R4a are independently selected from phenyl, thiazolyl and oxazolyl wherein the phenyl, thiazolyl or oxazolyl ring is unsubstituted or substituted with a substituent selected from (i) halo, (ii) loweralkyl, (iii) hydroxy, (iv) alkoxy and (v) thioalkoxy; and R* is phenyl, halo-substituted phenyl, dihalo-substituted phenyl, alkoxy-substituted phenyl, loweralkyl-substituted phenyl, bis-trifluromethyl-substituted phenyl or naphthyl or loweralkyl; or an acid addition salt thereof.
Preferred compounds of the formula A4 are those wherein R4a is phenyl and R* is phenyl. Most preferred compounds of the formula A4 are those wherein R4 and R4a are phenyl and R* is phenyl.
The compounds of the invention can be prepared as shown in Schemes 1-9. As outlined in Scheme 1, coupling of protected xcex1-aminoaldehyde Ia and Ib (R30 is loweralkyl or benzyl) with VCI3(tetrahydrofuran)3 and Zn produces a mixture of diols, out of which compounds II and III can be isolated. Hydrolysis of II and III with barium hydroxide leads, respectively, to diaminodiols IV and V. Alternately, treatment of II with xcex1-acetoxyisobutyryl bromide in acetonitrile leads to compound VI, which upon hydrolysis with barium hydroxide, produces diaminodiol VII. In a preferred embodiment, R4 and R4a are each phenyl and the first reaction in Scheme 1 is a dimerization. 
As outlined in Scheme 2, treatment of compound II with xcex1-acetoxyisobutyryl bromide in hexane/dichloromethane produces bromoacetate VIII. Hydrolysis of VIII with concommitant cyclization produces epoxide IX, which is reduced with sodium borohydride and trifluoroacetic acid to produce compound X. Barium hydroxide hydrolysis of X leads to diamine XI. 
As outlined in Scheme 3, acylation of the enolate derived from compound XII with ethyl chloroformate gives compound XIII. Subsequent alkylation of the enolate prepared from XIII provides compound XIV (R4a is thiazolyl), which is hydrolyzed and decarboxylated to lactone XV. Hydrolysis of XV and protection of the hydroxyl group leads to compound XVI, which, upon treatment with diphenylphosphoryl azide undergoes a Curtius rearrangement. The intermediate isocyanate is trapped with benzyl alcohol to produce compound XVII. Desilylation of XVII with tetrabutylammonium fluoride provides compound XVIII, which is deprotected with HBr to give diamine XIX.
In a preferred embodiment of the process shown in Scheme 3, R4 is phenyl. 
As outlined in Scheme 4, compound XX (R3 is loweralkyl) is converted to isocyanate XXI by treatment with phosgene. Alternatively, treatment of XX with 4-nitrophenyl chloroformate produces carbamate XXII. Condensation of either XXI or XXII with compound XXIII wherein Z is O, S or N(R8), with catalytic 4-dimethylaminopyridine as needed, provides compound XXIV. Lithium hydroxide hydrolysis of XXIV produces compound XXV. In a preferred embodiment of the process shown in Scheme 4, n is 1. 
As outlined in Scheme 5, compound XXVIII, which represents diamines IV, V, VII, XI and XIX, is acylated with an activated derivative of XXVI having the formula (R6)(R7)CHOC(O)OL wherein L is an activating group for the acylation reaction such as p-nitrophenyl, phenyl, N-succinimidyl, N-phthalimidyl, N-benzotriazolyl, N-5-norbornene-2,3-carboxamidyl or 2,4,5-trichlorophenyl and the like (for example, XXVII, which is prepared by reacting XXVI with 4-nitrophenyl chloroformate) to provide a mixture of compounds XXIXa and XXIXb or an acid addition salt thereof. Coupling of XXIXa or XXIXb to compound XXX by treatment with a carbodiimide (or by reaction with an activated ester of XXX) produces compound XXXIa or XXXIb, respectively. In a preferred embodiment of the process shown in Scheme 5, n is 1, R4 and R4a are each phenyl, X is H and Y is OH. 
As outlined in Scheme 6A, treatment of diamine XI with a boronic acid (preferably, phenylboronic acid) or a boroxine produces compound XXXII, which is selectively acylated with an activated derivative of XXVI having the formula (R6)(R7)CHOC(O)OL within L is an activating group for the acylation reaction such as p-nitrophenyl, phenyl, N-succinimidyl, N-phthalimidyl, N-benzotriazolyl, N-5-norbornene-2,3-carboxamidyl or 2,4,5-trichlorophenyl and the like (for example, XXVII) to provide compound XXXIIIa or an acid addition salt thereof. Carbodiimide-mediated coupling of XXXIIIa to compound XXX (or reaction of XXXIIIa with an activated ester of XXX) leads to compound XXXIVa. In a preferred embodiment of the process shown in Scheme 6A, n is 1, R4 and R4a are each phenyl and R* is phenyl.
Alternatively, compound XXXII can be acylated with compound XXX (or an activated ester thereof) to provide compound XXXIIIb or an acid addition salt thereof. Acylation of compound XXXIIIIb with an activated derivative of XXVI having the formula (R6)(R7)CHOC(O)OL wherein L is an activating group for the acylation reaction such as p-nitrophenyl, phenyl, N-succinimidyl, N-phthalimidyl, N-benzotriazolyl, N-5-norbornene-2,3-carboxamidyl or 2,4,5-trichlorophenyl and the like (for example, XXVII) provides compound XXXIVb. 
Scheme 6B outlines an alternative preparation of XXXIIIa or XXXIIIb. Reaction of compound XI with (i) two equivalents of B(OR**)3 wherein R** is loweralkyl (preferably, isopropyl) or (ii) two equivalents of B(R***)3 wherein R*** is halo (preferably, fluoro) and four equivalents of an amine such as triethylamine in an inert solvent such as tetrahydrofuran, followed by reaction with an activated derivative of XXVI having the formula (R6)(R7)CHOC(O)OL wherein L is an activating group for the acylation reaction such as p-nitrophenyl, phenyl, N-succinimidyl, N-phthalimidyl, N-benzotriazolyl, N-5-norbornene-2,3-carboxamidyl or 2,4,5-trichlorophenyl and the like (for example, XXVII), gives compound XXXIIIa or an acid addition salt thereof. Similarly, reaction of compound XI with two equivalents of B(OR**)3 wherein R** is loweralkyl (preferably, isopropyl) or two equivalents of B(R***)3 wherein R*** is halo (preferably, fluoro), followed by reaction with compound XXX (or an activated ester derivative thereof), gives compound XXXIIIb or an acid addition salt thereof. In the preferred embodiment of the process shown in Scheme 6B, n is 1, R4 and R4a are each phenyl and R** is isopropyl or R*** is fluoro. 
Scheme 6C outlines an alternative preparation of XXXIVa and XXXIVb. Reaction of compound XI with two molar equivalents of Ti(OR****)4 wherein R4 is loweralkyl (preferably, isopropyl), followed by reaction with an activated derivative of XXVI having the formula (R6)(R7)CHOC(O)OL wherein L is an activating group for the acylation reaction such as p-nitrophenyl, phenyl, N-succinimidyl, N-phthalimidyl, N-benzotriazolyl, N-5-norbornene-2,3-carboxamidyl or 2,4,5-trichlorophenyl and the like (for example, XXVII), provides compound XLII or an acid addition salt thereof. Reaction of compound XLII with compound XXX (or an activated ester derivative thereof) gives compound XXXIVb. Similarly, reaction of compound XI with two molar equivalents of Ti(OR****)4 wherein R4 is loweralkyl (preferably, isopropyl), followed by reaction with compound XXX (or an activated ester derivative thereof), provides compound XLIII or an acid addition salt thereof. Reaction of compound XLIII with an activated derivative of XXVI having the formula (R6)(R7)CHOC(O)OL wherein L is an activating group for the acylation reaction such as p-nitrophenyl, phenyl, N-succinimidyl, N-phthalimidyl, N-benzotriazolyl, N-5-norbornene-2,3-carboxamidyl or 2,4,5-trichlorophenyl and the like (for example, XXVII) gives compound XXXIVa. In the preferred embodiment of the process shown in Scheme 6C, n is 1, R4 and R4a are each phenyl and R**** is isopropyl. 
Scheme 7 shows an alternative preparation of diaminomono-ol XI. Reaction of ketonitrile XXXV with Grignard reagent R4aCH2MgX provides ketoenamine XXXVI. Reaction of the ketoenamine with NaBH4CH3SO3H, followed by reaction of the resulting intermediate (without isolation) with NaBH4/CF3CO2H, provides XXXVII. Hydrogenation of the benzyl groups gives XI. Alternatively, protection of the free amino group of XXXVII as the t-butyloxycarbonylamino group, followed by hydrogenation of the benzyl groups, gives XXXVIII. In a preferred embodiment, R4 and R4a are each phenyl. 
Scheme 8 shows an alternative preparation of XXXVIII. N-protection of XXXVI gives XXXIX. Reaction of XXXIX with borane-tetrahydrofuran complex, followed by reaction of the resulting product with LiAlH4 or KBH4, provides the N,N-dibenzyl precursor to XXXVIII. 
Scheme 9 shows how the selectively protected diamine XXXIX can be used to prepare compounds of the invention XL and XLI. 